Current supply system



March 28, 1950 A. L. QUIRK 2,502,342

CURRENT SUPPLY SYSTEM Original Filed Dec. 9, 1944 fizveiziar Jrlkzaal fiaz'r/Z Patented Mar. 255%, l

UNITED STATES PATENT OFFICE CURRENT SUPPLY SYSTEM Arthur L. Quirk, North Providence, R. L, assignor to Harvey Radio Laboratories, Inc., Cambridge, Mass, a corporation of Massachusetts 3 Claims.

This invention relates to current supply systems and more particularly to voltage regulator systems of the type using electronic rectifying and control tubes.

This application is a division of application Serial No. 567,510, filed December 9, 1944, now Patent No. 2,464,940, issued March 22, 1949.

Objects of the invention are to provide a system which is simple and economical in construction, which is durable and reliable in use, which afiords close regulation of the voltage, which minimizes filter ripple, which affords many different voltages from a single constant-voltage source, and which is generally superior to prior systems of the character referred to.

In one aspect the present invention involves a voltage regulating system comprising a regulator tube having a cathode, plate and control grid, a control tube having a cathode, plate, control grid and screen grid, a constant-voltage device having a substantially constant voltage drop throughout a range of loads, a supply circuit connected to the plate of the regulator tube, a load circuit having one end connected to the cathode of the regulator tube, a regulating circuit interconnecting the plate of the control tube and the cathode of the regulator tube, a load resistance in the regulating circuit, means for varying the bias of the control grid of the control tube in proportion to voltage variations in the load circuit, a circuit interconnecting one end of the constant-voltage device and the cathode of the control tube, the other end of the device being connected to the other end of the load circuit, a control circuit containing a control resistance, and a branch circuit interconnecting the control resistance and the screen grid of the control tube, characterized in that the control circuit is connected across the supply circuit so that variation in the voltage of the supply circuit directly varies the bias of the screen grid of the control tube to help regulate the voltage in the load circuit. Preferably the aforesaid means for varying the bias of the control grid of the control tube comprises a primary control circuit connected across the load circuit, a primary branch control resistance in the primary control circuit and a primary circuit interconnecting the primary resistance and the control grid of the control tube, and the aforesaid control resistance is located in a secondary control circuit connected across the supply circuit with a secondary branch circuit interconnecting the secondary resistance and the screen grid of the control tube.

In another aspect the invention involves a current supply system comprising an electrical circult, a relay having contacts for controlling the circuit, a circuit switch in series with the contacts for conjointly controlling the circuit, a relay switch for controlling the relay, each of the switches having open, closed and intermediate positions, the circuit switch having its closed and intermediate contacts interconnected so that the circuit is closed when the switch is in either closed or intermediate position or moving from one to the other, and means interconnecting the switches for conjoint operation so that they are always in corresponding positions, whereby the circuit is first closed by the circuit switch when the switches are moved from open to intermediate position and then closed by the relay contacts after the switches have been moved to closed position.

In a more specific aspect the system comprises a tube having a cathode and anode, a main circuit for supplying plate current to the tube, an auxiliary circuit for supplying heating current to the cathodes, a relay having contacts for closing the main circuit, a main switch in series with the contacts for conjointly controlling the main circuit, an auxiliary switch for controlling both the auxiliary circuit and the relay, a relay switch in series with the auxiliary switch for conjointly controlling the relay, the main and relay switches each having open, closed and intermediate positions, the main switch having its closed and intermediate contacts interconnected so that the circuit is closed when the switch is in either closed or intermediate position or moving from one to the other, and means interconnecting the main and relay switches for conjoint operation so that they are always in corresponding positions, whereby the main circuit is first closed by the main switch when the main and relay switches are moved from open to intermediate positions and then closed by the relay contacts after all three switches have been moved to closed positions. Preferably the relay is slowacting so that the main circuit is not closed until a predetermined time after heating current is supplied to the cathode. In the preferred embodiment the main and relay switches each has two closed positions, together with means for supplying different voltages when the main switch is in the closed positions respectively.

For the purpose of illustration a typical embodiment of the invention is shown in the accompanying drawings in which Fig. 1 is a circuit diagram;

Fig. 2 is a side view of a switch; and

Fig. 3 is an axial section of one element of the switch.

The particular embodiment of the invention chosen for the purpose of illustration comprises a supply circuit including conductors l and 2 and a load circuit including conductors 3 and l, the load being indicated at 6. Current is supplied from a suitable source through a fullwave rectifier comprising tubes 1 and 8, each comprising a cathode 9 and an anode H, and thence through a choke input filter including inductances l2 and condensers 13.

Connected in parallel between the conductors 2 and 3 are three regulating tubes l2 each having a cathode l3, a control grid M, a screen grid [6 and a plate ll, the plates and screen grids being connected to conductor 2, the cathodes being connected to conductor 3 and the control grids being interconnected through conductors H and i8 and resistances l9, 2? and 2 l.

The voltage regulating portion of the system also comprises a control tube 22 comprising a cathode 23, a control grid 2 a screen grid 26, a suppressor grid 2'! and a plate 28. The cathode 23 and suppressor grid 21 are connected together and then to ground through three constantvoltage tubes 29. Plate 28 is connected to conductor l8 and a load resistance 31 is interposed between the conductors fl? and I3. Connected across the load circuit is a primary control circuit comprising branches 32 and 33 and branches 3t and 3?, the two pairs of branches being interconnected through a common portion 38. The portions of the network are interconnected by switches il, i2 and 43 which have right-hand positions in which they interconnect the branch circuits 33 and 31', left-hand positions in which they interconnect the branch circuits 32 and 36 and intermediate positions in which the circuits are open. The control grid 24 of the control tube 22 is connected to an adjustable tap on the resistance 38 through a primary branch circuit 44 containing a resistance lli.

Interconnected between the conductor ii and ground is a secondary control circuit ll containing resistor G8, and a secondary branch circuit i3 interconnects the secondary control circuit with the screen grid 2.5 of the control tube 22. Branch wire 15 can be connected to a selected tap of a series of taps 58 of resistor Q8, or a selected voltage may be derived from potentiometer 48 by means of a sliding tap.

Current is supplied to the rectifier tubes 1 and 8 through transformers i and 52, transformer 5i supplying heating current to the cathodes t and transformer 52 supplying the plate current. Transformer 5i is connected to a source of alternating current through an auxiliary circuit 53 including a switch a fuse 56, a pilot light 51 and condensers 55%. The transformer 52 is connected to the source of alternating current through a circuit 6i including relay contacts 62, a manual switch 63, a fuse i and two branches 6G and El, a pilot lamp t8 and condensers 69. The relay 62 is controlled by a winding H c0n- 4 nected to the source of alternating current through switch 12, conductors l3 and "M and the switch 5 1. The relay ll may be of any slowacting type, as for example the thermostatic type diagrammatically illustrated in Fig. l.

lhe switches 63 and l2 each has a mid-position in which it is open, two closed positions and an intermediate position between the mid-position and each of the closed positions. In the case of switch 63 the closed and intermediate positions are interconnected so that the circuit is closed when the switch is in either closed or intermediate position or moving from one to the other. When the switch is moved upwardly the entire primary of the transformer 52 is connected in circuits through conductor 66, and when the switch is moved downwardly only a portion of the primary of the transformer is connected in circuit through the conductor til. The switches 53 and 12 are interconnected with each other and with the switches ll, 42 and 43 so that they all move together. The multiple switch also includes a switch l5 for shunting one of the constant voltage tubes 29.

As illustrated in Figs. 2 and 3, a suitable multiple switch comprises a frame 8| carrying a plurality of rings 82 of insulation, a shaft 83 journa led in the frame, a handle 84 for rotating the shaft, a plurality of disks 86 of insulation mounted on the shaft 83 inside the rings 32 respectively, a conducting ring 81 mounted on one side of each disk 65, a conducting wiper 88 mounted on each ring 82 and engaging the adjacent conducting ring 81 in all positions of the rotor, a series of conducting terminals 9!, 92, 93, and mounted on the other side of each ring 82, these contacts corresponding to the live contacts of each of the switches 41, 42 43, 53, "I2 and 16. shown in Fig. 1, and a conductin finger 96 mounted on each disk 36 the finger 96 being interconnected with the adjacent conducting ring 81 and: engaging one of the contacts 9| to 95 in each of the five positions of the switch. The multiple switch is so connected that when the, switches 83, 12 and 16 are in their upper positions the switches il, 42 and 43 are in their right-hand positions, and when the switches 63, 12 and 15 are in their lower positions the switches 4|, 42 and 43 are in their left hand positions.

To start the operation of the system the switch 54 is first closed to supply heating current through the auxiliary circuit 53 to the cathodes 9 of the rectifier tubes 8. Then the multiple switch is moved from the mid-position to the right or left depending upon the voltage desired. If moved to the high voltage side where part of the, primary of transformer 52 is included, the switches M, 12 and 43 occupy their right-hand positions wheremore resistance is included and the switch it. occupies its lower position where the lower tube 29, is. not shunted. When the switch is turned in the opposite direction contact 63 connects with conductor 61 to include all of the primary of the transformer 52, the switches il, 42 and 43 occupy their right-hand positions to include a lesser amount of resistance in the circuit and the switch it occupies its upper position in which the lower tube 29 is shunted.

When the switch $3 is. first closed current is not supplied to the transformer 52 because the slow acting relay H is still open. However switch l2 closes when the multiple switch reaches closed position, thereby supplying current to the relay, 1 I. After a predetermined time the relay closes its contacts 62 thereby completing the circuit to the transformer 52. Thus, even if the multiple switch is closed at the same time as the auxiliary switch 56, voltage is not impressed upon the supply circuit until the cathodes 9 are heated. Likewise if the multiple switch is closed before the auxiliary switch 54 is closed, voltage is not impressed upon the plate circuit of the rectifier tubes until the relay lli has had time to operate because the relay switch i2 is in series with the auxiliary switch 5 3. Thus the rectifier tubes can not be damaged by impressing voltage on the plate circuit before the cathodes have been heated.

From the foregoing it will be evident that a characteristic feature of the invention consists in that the secondary control circuit ll is con nected to supply conductor 2, the voltage of which is not regulated, instead of the conductor 3, the voltage of which is regulated. Thus sudden changes in the unregulated voltage input will have a greater effect on the control tube than would the variations of the regulated output if the secondary control circuit ll were connected to the conductor 3 instead of to the conductor 2. In other words the change in screen voltage is a larger fraction of the normal screen voltage than would be the case if the screen were subjected to the lower voltages existing on the regulated side. Also if there is a sudden drop in voltage because of heavy load, before the regulator action begins the control grid 24 0f the control tube 22 becomes more negative as the plate current decreases. At the same time the screen voltage decreases, more than it would if fed from the regulated side, causing a further decrease in the plate current of tube 22. Hence the voltage drop in the load resistor 3i decreases, the bias on tubes i2 becomes less negative, and a larger current passes through tubes 2 to compensate for the tendency for the voltage to drop. Likewise small voltage variations, such as ripples, are smoothed out more eiiectively because the screen voltage varies a larger percentage of its normal value when fed from the unregulated side 2.

A characteristic feature of the present invention is the exceptionally wide voltage range achieved by the aforesaid switching arrange ment. For example, when fed from a 110 volt source the system may supply '700 to 1,000 volts when a part of the transformer 52 is cut out and 560 to 700 volts when the entire transformer is used. The relay H not only protects the rectifier tubes 8 as above described but also eliminates arcing at the switch 63. When the multiple switch is moved from closed to open position the relay switch l2 opens at the beginning of the switch movement, thereby causing the relay H to open the circuit at contacts 62, Whereas the switch 63 does not open until the multiple switch has passed the intermediate position between open and closed positions.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. Apparatus of the character referred to comprising a regulator tube having a cathode, plate and control grid, a control tube having a cathode, plate, control grid and screen grid, a constantvoltage device having a substantially constant voltage drop throughout a range of loads, a supply circuit connected to the plate of the regulator tube, a load circuit having one end com nected to the cathode of the regulator tube, a regulating circuit interconnecting the plate of the control tube and the cathode of the regulator tube, a load resistance in said regulating circuit, means for varying the bias of the control grid of said control tube in proportion to voltage variations in the load circuit, a circuit interconnecting one end of said constant-voltage device and the cathode of the control tube, the other end of the device being connected to the other end of the load circuit, a control circuit containing a control resistance, a branch circuit interconnecting said control resistance and the screen grid of the control tube, said control circuit being connected across said supply circuit so that variation in the voltage of the supply circuit directly varies the bias of the screen grid of the control tube to help regulate the voltage in the load circuit, a rectifier tube having a cathode and anode for delivering current to said supply circuit, a main circuit for supplying plate current to said rectifier tube, an auxiliary circuit for supplying heating current to the cathode of the rectifier tube, a relay having contacts for closing the main circuit, a main switch in series with said contacts for conjointly controlling the main circuit, an auxiliary switch for controlling both the auxiliary circuit and the relay, a relay switch in series with said auxiliary switch for conjointly controlling the relay, a control switch for varying said load resistance, said main, relay and control switches each having two closed positions, an open position between the two closed positions, and an intermediate position between the open position and each closed position, means for supplying different voltages when the main switch is in its closed positions respectively, the main switch having its closed and intermediate contacts interconnected so that the circuit is closed when the switch is in either closed or intermediate position or moving from one to the other, the control switch including diiferent amounts of said load resistance in the regulating circuit when in its closed positions respectively, and means interconnecting the main, relay and control switches for congoint operation so that they are always in corresponding positions.

Apparatus or the character rer'erred to comprising a supply circuit including a source adapted to furnish two voltage values and main switch means for changing from one voltage value to the other, a load circuit, a regulator tube having a control grid and being with its plate connected to said supply circuit, a control tube having a control electrode, and a plate connected to said control grid of said regulator tube, a load circuit connected between the cathodes of said regulator and said control tubes, a regulating resistor between the grid and the cathode of said regulator tube, variable control resistor means between the cathode of said regulator tube and said load circuit, control switch means for varying the resistance of said resistor means from one value to another, and a connection from said control electrode to a tap of said resistor means, said main switch means and said control switch means being interconnected positively to establish a resistance value of said control resistor means which corresponds to a respective one of said two voltage values.

3. A voltage regulator having input and load terminals comprising a regulator tube having a control electrode, a cathode connected to a load terminal and an anode connected to an input terminal, a control tube having a control grid, a screen grid, an anode connected to said control electrode, and a cathode, a constant voltage drop device connected directly between the cathode of the control tube and the other input and load terminals, a load resistor between control electrode and cathode of said regulator tube, an output resistor connected between the load terminals, an input resistor inserted between the input terminals directly and, without deviation to the cathode of said control tube, a direct connection between said control grid and a tap of said output resistor, and a connection between said screen grid and a tap of said input resistor, whereby the potential or" said screen grid depends solely upon the unregulated input REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,764,283 Strong June 17, 1930 2,117,138 Bock May 10, 1938 2,268,790 White et a1 Jan. 6, 1942 2,323,857 Trevor l- July 6, 1943 2,377,500 Johnson June 5, 1945 2,416,922 Irish Mar. 4, 1947 2,443,541 Neustadt June 15, 1948 

